1. Field of the Invention
The invention relates in particular to a method for protection of an energy storage source, in particular a motor vehicle battery.
2. Description of Related Art
Patent EP 920 722 B1 describes a system for regulation of a generator on a motor vehicle.
It is known to impose on a rotary electric machine such as an alternator a functioning mode which is selected from amongst a plurality of predetermined modes.
These modes are imposed by a states machine, and correspond for example to the following modes:                Stoppage mode, known as the STAND_BY mode, in which the excitation of the rotor is maintained at 0% in cyclical ratio terms;        Timing mode, known as the TIMER mode, in which the excitation is cut off for a predetermined time, for example for 5 seconds during starting;        Pre-excitation mode of the rotor, known as PRE_EXC, during which the cyclical ratio is maintained at approximately 12.5% for example (an object of this mode is to magnetize the rotor in order to be able to measure the phase frequency before the normal regulation mode, as soon as rotation begins);        Progressive response mode, known as LRC mode, during which the cyclical ratio varies between 0 and 100%;        Normal regulation mode, known as NORMAL mode, during which the cyclical ratio varies according to the battery charge in particular;        Phase regulation mode.        
The alternator is generally connected to a voltage regulator and to a battery, in a known manner.
One or a plurality of sensors for the speed of rotation of the rotor of the alternator can be provided, and one or a plurality of phase screws (this screw permitting a mechanical connection and an electrical connection between the phases of the stator and the regulator) enable the voltage regulator to obtain information which is representative of this speed of rotation.
This can make it possible to start generating output current of the alternator above a certain speed, for example 800 rpm.
In the event of accidental disconnection of the phase screw on the vehicle, the regulator may be deprived of the possibility of obtaining information on the speed of rotation of the alternator, and this regulator, when it is functioning in pre-excitation mode PRE_EXC, may remain blocked functioning in this pre-excitation mode.
This situation can become dangerous because of possible overloading of the battery, giving rise to excess voltage on the network on board the vehicle, in the case when the alternator functions for a prolonged period of time in the pre-excitation mode (in particular despite an alert given for example by a lamp, with the driver of the vehicle ignoring this alert).
The invention is intended in particular to eliminate this type of problem.